Embodiments of the present invention generally relate to apparatus and methods for temporarily sealing a pipe. More specifically, the present invention relates to apparatus and methods for creating a temporary airtight seal at the open end of a pipe in a plumbing or refrigeration system.
Refrigeration systems are typically comprised of an evaporator that vaporizes liquid refrigerant to cool the surrounding environment; a compressor that highly pressurizes the recently evaporated refrigerant; and a condenser that returns the refrigerant to a liquid state. Each of these components is typically connected by pipes or other fluid conduits. The entire system is airtight (i.e., no air from the outside environment can enter the system). Refrigeration systems must be airtight so that: pressure is maintained in the various pipe lines; no refrigerant leaks out of the refrigeration system; and no air or other contaminants from the surrounding environment enters the pipes.
Refrigerants utilized in refrigeration systems are typically liquid compounds with appropriate thermodynamic properties to undergo a phase change from liquid to gas in order to cool the surrounding environment. As refrigerant evaporates, it absorbs heat energy from the environment thereby decreasing the temperature of the environment. Many compounds are known in the art that possess the thermodynamic properties appropriate for use in a refrigeration system. One such compound is chlorodifluoromethane, which is also known as HFCF-22 or R-22. However, this compound and other similar compounds are believed to have negative environmental effects such as ozone depletion. Therefore, use of chlorodifluoromethane and other compounds with similar environmental consequences is being reduced or eliminated, and alternative compounds that do not effect the same environmental consequences are being utilized. One such new replacement refrigerant is R410A, which is also known as AZ-20 or Puron, and it is a mixture of compounds including the synthetic oil polyoester. The chemical nature of this mixture causes the refrigerant to be highly hygroscopic. That is, R410A refrigerant strongly attracts and absorbs water molecules from the surrounding environment.
As refrigerants that are believed to have negative environmental consequences are no longer being manufactured and will eventually become unavailable for purchase or use, existing refrigeration systems incorporating these outdated refrigerants will eventually require an upgrade to accommodate the newer refrigerants. That is, to repair a refrigeration system that incorporates an unavailable refrigerant, it may be necessary to replace the existing condenser with a new condenser compatible with currently available refrigerants. This process involves cutting the existing pipe lines; removing the old condenser; and installing a new condenser and evaporator that utilize the new refrigerant.
Cutting pipes may also be required if pipes and fluid conduits become damaged or corroded. For example, a pipe may become corroded over time due to surrounding environmental conditions. Additionally, existing plumbing lines are sometimes accessed in order to add new fluid lines for system additions. Regardless of the reason, pipes and other fluid conduits are typically serviced by removing a portion of the conduit (e.g., the portion of the conduit that is damaged) and replacing it with a new piece of conduit.
In a refrigeration system, the open end of the pipe that has been cut must be sealed quickly in order to prevent air and water contamination and to quickly recreate the airtight system. This is even more critical with newer hygroscopic refrigerants, which are more susceptible to contamination due to their strong attraction of water from the surrounding environment. That is, if a hygroscopic refrigerant such as R410A is utilized in the refrigeration system, water moisture in air that enters a refrigeration system is quickly absorbed by the refrigerant oil, thereby causing contamination. When the system is reassembled, the lines and/or existing components which contain the hygroscopic polyoester oil must now be thoroughly cleaned through a process known in the art as nitrogen purging and triple evacuating, a very time consuming effort. Such contamination effects other negative consequences including, but not limited to: reduced cooling performance; malfunction of the evaporator; increased compressor noise; and/or compressor failure.
In non-hygroscopic systems, any contamination due to the entry of air into the refrigeration system may be remedied by vacuum purging the air prior to use of the system. However, since a hygroscopic refrigerant is contaminated by both water and air, it generally must be discarded and replaced by new refrigerant as water cannot be removed as easily as air. Therefore, sealing the open end of a cut pipe in a relatively short time frame is even more critical for hygroscopic systems to prevent the time and cost associated with refrigerant replacement.
One method commonly known in the art for temporarily sealing the open end of a pipe is to pinch it closed and then braze the edges together. That is, the metal walls of the pipe are compressed until the opening created by the cut is closed. An airtight seal is then created by joining the edges of the metal walls via heating of a filler metal alloy to a temperature at which the filler metal alloy melts and flows between the pinched edges of the fluid conduit as is commonly known in the art. Such a method effectively creates an airtight seal at the open end of the cut pipe. However, as is commonly known in the art, this method can take a relatively long period of time to implement and results in formation of oxidation residue on the interior surface of the fluid conduit. Additionally, upon connection of the sealed fluid conduit with other components, the portion of the fluid conduit affected by the airtight seal (i.e., the portion of the fluid conduit that is pinched closed and brazed to create an airtight seal) must be removed prior to connection of other components. The removal process is time consuming and can result in excessive refrigerant contamination.
Another way to create a temporary air-tight seal on the open end of a pipe is to couple an apparatus to the outer diameter of the pipe that grips the outer surface of the pipe via a plurality of teeth. That is, such a method grips the outer surface of the pipe with the teeth of the apparatus with sufficient strength to maintain an elevated internal pressure in the pipe and an air-tight seal between the interior of the pipe and the surrounding environment. As the internal pressure of the pipe is increased, the force with which the teeth grip the outer surface of the pipe increases. While providing an air-tight seal for the open end of a pipe, the teeth may also scar or mar the outer surface of the pipe, thereby necessitating removal of the pipe end to maintain the integrity of the piping and/or refrigeration system.
Also known in the art, a temporary air-tight seal may be created on the open end of a pipe via coupling of an apparatus to the open end of a pipe and then securing the apparatus via adhesion of the apparatus to the outer surface of the pipe. That is, an adhesive is applied to the one or more of the internal surfaces of the apparatus such that the surfaces will contact and adhere to the outer surface of the pipe upon installation of the apparatus. While providing an air-tight seal for the open end of a pipe, use of an adhesive prevents easy and/or rapid removal of such an apparatus from the open end of a pipe. It can also necessitate removal of the pipe end to maintain the integrity of the piping and/or refrigeration system.